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simple question

Altera_Forum
Honored Contributor II
759 Views

Hi there, 

I'm trying to increment a row of leds by one but pressing a pushbutton that is normally high until it is pressed. I have this code, but for some reason, the led's just light randomly. I'm using a DE2-70 board, 18 LEDs, 1 pushbutton to reset, and 1 to increment.  

 

module button_led(iKEY, oLEDR, iCLK_28); 

output [17:0]oLEDR; 

input [0:3]iKEY; 

input iCLK_28; 

reg [17:0]j; 

 

assign oLEDR = j; 

 

always @(posedge iCLK_28) 

begin  

if(!iKEY[0]) 

j <= 0; 

else if (!iKEY[1]) 

j <= j + 1; 

end 

 

endmodule 

 

Thanks!!
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4 Replies
Altera_Forum
Honored Contributor II
59 Views

Your code is exactly doing what you have written: increment the counter while the key is pressed. You apparently intended to increment it by one for each falling edge of the key signal. 

 

The key inputs are said to have debouncing circuits in the DE2-70 manual. If this is correct, the below code (synchronous edge detection) should work. 

reg k1; reg k2; always @(posedge iCLK_28) begin k1 <= KEY; k2 <= k1; if(!iKEY) j <= 0; else if (!k1 && k2) j <= j + 1; end
Altera_Forum
Honored Contributor II
59 Views

Thanks for the reply! 

I'll try your code tomorrow when i get the chance. I realize that i was incrementing awkwardly like that, but i also tried: 

 

always @ (negedge iKEY[1]) 

j <= j+1; 

 

but that didn't give any sort of response..
Altera_Forum
Honored Contributor II
59 Views

hmm, the code still doesn't light any LEDs. any ideas?

Altera_Forum
Honored Contributor II
59 Views

I'm sorry, i forgot to import the assignments -_-. it works perfectly thanks!

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